Tractor-shovel with pivotal steering means

ABSTRACT

A tractor-shovel comprises two carriages, one for a shovel and one for a motor, connected by two pivotal joints located at either side of the longitudinal axis of the vehicle. The joints are pivoted about vertical axes, and steering of the tractorshovel is effected by laterally displacing one of the joints along the drive direction while holding the other joint fixed.

United States Patent 1191 1111 3,809,176 Von Braunschweig 1 May 7, 1974 [54] TRACTOR-SHOVEL WITH PIVOTAL 3,521,719 7/1970 Forpahl 180/51 STEERING MEANS 3,312,301 4/1967 Hagen ISO/79.2 B 3,507,352 4/l970 Williamson... l80/79.2 B X Inventori Georg Von Braunschwelg, 3,439,937 4/1969 Dixon ISO/79.2 B x Krahenwinkel, Germany 73 Assignee: Firma Rheinstahl Aktiengesellschaft FOREIGN PATENTS 0R APPLICATIONS Hanomag Baumaschinen, Hannover, 9,235 4/1904 Great Britain 180/792 B Germany Filed! p 1972 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Eu ene H. Eickholt 21 1. N 2 7 013 g 1 App 0 8 Attorney, Agent, or Firm-Roland l. Griffin [30] Foreign Application Priority Data Sept. 8, l97l Germany 2144909 {57] ABSTRACT [52] US. Cl. ISO/79.2 B, 280/468, 280/400, A tractor shove] comprises two carriages, one for a 37/4 shovel and one for a motor, connected by two pivotal [5 l] Int. Cl B62d 5/00 joints located at either Side of the longitudinal axis of [58] Fleld of Search l80/485l, the vehicle The joints are pivoted about vertical axes l80/79-79.5; 280/DIG. 9, 468, 463, 400; 37/ and steering of the tractor-shovel is effected by laterally displacing one of the joints along the drive direcl561 References (311 tion while holding the other joint fixed.

UNITED STATES PATENTS 3,367,437 2/1968 Garrett 180/792 B 8 Claims, 5 Drawing Figures mgmmm 11914 $809,176

- sum 2 GF 4 I Fig.2

PATENTEDHAY mm 3.809176 SHEET 3 0F 4 LLA Fig.3

TRACTOR-SHOVEL WITH PIVOTAL STEERING MEANS BACKGROUND OF THE INVENTION This invention relates to tractor-shovels comprising a front carriage for rigidly supporting shovel means and a hind carriage for supporting a motor, the hind carriage being provided with a jointed cross-shaft axle or a single-wheel suspension, where both carriages are pivotally connected with each other and have steering drive means for steering purposes.

Tractor-shovels of this kind are disclosed, for example, in prepublished German Pat. applications Nos. 1,481,323 and 1,137,681. They are provided with a socalled kink steering which comprises an upright pin located on the longitudinal axis of the tractor-shovel and bearing lugs directly connected to both carriages. Hydraulic piston-cylinder aggregates are provided which act laterally to the longitudinal axis and thereby cause steering movements around the upright pm. All forces and stresses appearing between both carriages are sustained by this connection. At construction sites where there are often large undulations in the ground surface, pitching motions between the front and hind carriages are generated because of this central joint arrangement. These pitching motions adversely affect the drivin g characteristics and directional stability of such tractor-shovels.

Furthermore, German Pat. No. 958,619 discloses that with trucks the trailer may be coupled to the motor vehicle by means of upright joints in a double-acting frame joint. In the case of straight-line motion, both vehicles are moved together until they almost touch each other, while in the case of lateral movements, the inner joint in the curve always forms the kink or breakpoint of both coupled vehicles. The coupling of both vehicles is obtained by diagonal-bogie coupling in two levels, where the coupling elements each engage joint pins located at the outer edges of the vehicles. The diagonal struts sustain all the stresses, and the leverage for straight-line motion is especially unfavorable since the diagonal struts are positioned close to each other and considerable forces act on the joint pins traversely to the longitudinal axis of the vehicles. Due to this arrangement both vehicles include their own steering means in order to make the double-acting frame joint work properly in the case of lateral movements.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the steering means, the drive characteristics, and the directional stability of tractor-shovels comprising two pivotally connected carriages.

According to the present invention, the front and hind carriages of a tractor-shovel are connected by two joints which are located at both sides of the longitudinal axis of the tractor-shovel and which are pivotally mounted along upright axes, each of the joints being independently displaceable in the drive direction by way of the steering drive means.

In one preferred embodiment of the present invention, at least one rod corresponding to each joint is provided to pivotally act on a bearing lug on one of the carriages. Each of these rods is displaceable relative to its bearing location on the other carriage by way of the steering drive means. One of the joints is always in a retracted position relative to the other joint for forming the steering axis according to the steering movement to be executed, whereas the other joint is extended to determine the angle of turn.

In another preferred embodiment, directional stability of the tractor-shovel is increased by making each of these rods in the form ofa vertical carrier disc or plate.

According to still another preferred embodiment, both joints may comprise a double-acting frame joint and the steering drive means for displacing or restrain ing the joints may comprise hydraulic piston-cylinder aggregates or screw, rope, or tooth-wheel drives.

In still another preferred embodiment, both halves of the double-acting frame joint are displaceable relative to each other by means of a single drive mechanism acting in the direction of the longitudinal axis of the tractor-shovel. In the case of straight-line motion, both frame joint halves are fixedly connected to the carriages by way of restraining means, while in the case of lateral movements, only one of the frame joint halves is held fixed with respect to the carriages.

According to still another preferred embodiment, the drive and restraining means for each frame joint half comprises a piston-cylinder aggregate which pivotally and directly acts on the axis of the upright joint and on the respective carriage which carries the stationary frame joint bearing. Alternatively, the steering drive and restraining means for each frame joint half may comprise a piston-cylinder aggregate which pivotally acts on the corresponding carriage and on the frame joint plate at the side of that carriage.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram representing a top view of a tractor-shovel including kink steering means in accordance with a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram representing a side view of the tractor-shovel of FIG. 1 using cylindrical pusher rods in the kink steering means.

FIG. 3 is a schematic diagram representing a side view of the tractor-shovel of FIG. 1 using plate-like pusher rods in the kink steering means.

FIGS. 4 and 5 are schematic plan views illustrating a double-acting steering frame joint in accordance with two other embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, the tractor-shovel comprises a front carriage 1 supporting shovel means as well as a hind carriage 2 supporting motor means. The front wheels 3 are connected to carriage 1 by a rigid axle while the rear wheels 4 are either connected to carriage 2 by a jointed cross-shaft axle or by a single-wheel suspension.

Both carriages l and 2 are connected by two joints, one located on each side of the longitudinal axis A of the tractor-shovel. The joints are pivoted around upright axes LLA and RLA and may be displaced independently from eachother in the drive direction.

In the embodiments shown of FIGS. 1 through 3, the front carriage 1 includes bearing lugs 8L and SR on each side of the longitudinal axis A. These lugs engage pusher rods 5L and SR, which are displaceably guided in guidance bearings 6 of the hind carriage 2 and are moved by pivotally mounted piston-cylinder aggregates 7L and 7R.

In the embodiment shown in FIG. 2, cylindrical pusher rods 5L and SR are used, while in the embodiment shown in FIG. 3, plate-like pusher rods 5aL and SaR are used. Each of the plate-like pusher rods 5aL or 5aR is guided in bearings 6a and forms a very rigid connection with the bearing lugs 8aL or 8aR located one above another.

By extending the left pusher rod 5L (or SaL), the right steering axis RLA is formed by the right joint connection SR (or 511R) and SR (or 8aR) so that the tractor-shovel will make a right turn. When the right pusher rod 5R (orSaR) is extended, the left joint connection 5L- (or 5aL) and 8L (or 8aL) forms the left steering axis LLA.

In the embodiments of FIGS. 4 and 5, both joints comprise a double-acting frame joint. Several upright bearing lugs 9L are located on an axis along the front carriage 1 in a spaced relationship to each other. These bearing lugs, together with an upright frame joint plate 11, form one half of the double-acting frame joint, while correspondingly located right bearing lugs 9R at the hind carriage 2, together with the frame joint plate 1 1, form the other half of the double-acting frame joint.

In the embodiment of FIG. 4, a single piston-cylinder aggregate 12 is used to act on the pivot point 14 on the carriage 2, as well as on the pivot point 13 on the carriage 1, through the frame joint plate 11. By means of left and right restraining means L and 10R, the frame joint halves may be restrained for straight-line motion. In order to perform a steering movement for a right turn, it is necessary that the front carriage 1 be fixed relative to the hind carriage 2 by the right restraining means 10R, while the left restraining means 10L releases the front carriage so that the piston-cylinder aggregate 12 will displace both carriages l and 2 around the right steering axis. In order to perform a left turn the restraint and release of the frame joint halves are reversed. The restraining means 10L and IOR-shown here schematically may, for example, be moved by means of a tooth-wheel drive.

In an embodiment (not shown) similar to that of FIG. 4, a piston-cylinder aggregate is articulated at the carriage l and at the adjacent side of the frame joint plate 11. Another piston-cylinder aggregate is articulated at the opposing side of the frame joint plate 11 and at the hind carriage 2. This arrangement operates such that the piston-cylinder aggregates alternately form the restraining means or drive means, thus obviating the need for the lateral restraining means illustrated in FIG. 4.

In the embodiment shown in FIG. 5, two pistoncylinder aggregates l5 and 16 are used for alternately displacing or restraining the frame joint halves. These aggregates l5 and 16 are articulated at the carriages 1 and 2, respectively, and at the joint axes 9R and 9L, respectively. In this embodiment the piston-cylinder aggregates 15 and 16 also form the drive and restraining means simultaneously.

I claim:

1. A tractor-shovel comprising:

a front carriage and a hind carriage having a longitudinal axis;

pivotal connecting means for connecting the front and hind carriages, said pivotal connecting means including a first joint pivoted about a vertical axis and connecting the carriages on one side of a vertical plane including the longitudinal axis and a second joint pivoted about a vertical axis and connecting the carriages on the opposite side of the vertical plane including the longitudal axis; and

steering drive means connected to the first and second joints for displacing each joint independently of the other joint along a drive direction with respect to one of the carriages.

2. A tractor-shovel as in claim 1 wherein said pivotal connecting means comprises:

a first bearing lug and a second bearing lug each attached to one of the carriages;

a first rod and a second rod connected to the steering drive means and pivotally connected to the first and second bearing lugs to form the first and second joint, respectively; and

a first rod bearing and a second rod bearing mounted on the other of the carriages for guiding linear motion of the first and second rods, respectively, the steering drive means maintaining one of the rods in a retracted position and displacing the other of the rods relative to the carriage on which the rod bearings are mounted for turning the tractor-shovel, the joint formed by the retracted rod and corresponding bearing lug forming a steering axis and the amount of displacement of the displaced rod determining the angle of the turn.

3. A tractor-shovel as in claim 2 wherein each rod comprises a vertical plate.

4. A tractor-shovel as in claim 1 wherein:

the first and second joints comprise a double-acting frame joint; and

the steering drive means includes hydraulic pistoncylinder means for displacing the joints.

5. A tractor-shovel as in claim 4 wherein:

the double-acting frame joint comprises a first half and a second half; and

the pivotal connecting means further comprises restraining means for holding each frame joint half fixed relative to one of the carriages, both frame joint halves being restrained by the restraining means for straight-line motion, and one frame joint half being restrained by the restraining means and the other frame joint half being displaced by the hydraulic piston-cylinder means for turning.

6. A tractor-shovel as in claim 5 wherein the hydraulic piston-cylinder means and the restraining means comprise a first hydraulic piston-cylinder aggregate and a second hydraulic piston-cylinder aggregate, each pivotally connected to one of the carriages and one of the frame joint halves.

7. A tractor-shovel as in claim 5 wherein:

the double-acting frame joint includes a frame joint plate connecting the first and second joints; and

the hydraulic piston-cylinder means and the restraining means comprise a first hydraulic pistoncylinder aggregate and a second hydraulic pistoncylinder aggregate, each pivotally connected to one of the carriages and to the frame joint plate.

8. A tractor-shovel as in claim 5 wherein the restraining means is actuated by a tooth-wheel drive. 

1. A tractor-shovel comprising: a front carriage and a hind carriage having a longitudinal axis; pivotal connecting means for connecting the front and hind carriages, said pivotal connecting means including a first joint pivoted about a vertical axis and connecting the carriages on one side of a vertical plane including the longitudinal axis and a second joint pivoted about a vertical axis and connecting the carriages on the opposite side of the vertical plane including the longitudal axis; and steering drive means connected to the first and second joints for displacing each joint independently of the other joint along a drive direction with respect to one of the carriages.
 2. A tractor-shovel as in claim 1 wherein said pivotal connecting means comprises: a first bearing lug and a second bearing lug each attached to one of the carriages; a first rod and a second rod connected to the steering drive means and pivotally connected to the first and second bearing lugs to form the first and second joint, respectively; and a first rod bearing and a second rod bearing mounted on the other of the carriages for guiding linear motion of the first and second rods, respectively, the steering drive means maintaining one of the rods in a retracted position and displacing the other of the rods relative to the carriage on which the rod bearings are mounted for turning the tractor-shovel, the joint formed by the retracted rod and corresponding bearing lug forming a steering axis and the amount of displacement of the displaced rod determining the angle of the turn.
 3. A tractor-shovel as in claim 2 wherein each rod comprises a vertical plate.
 4. A tractor-shovel as in claim 1 wherein: the first and second joints comprise a double-acting frame joint; and the steering drive means includes hydraulic piston-cylinder means for displacing the joints.
 5. A tractor-shovel as in claim 4 wherein: the double-acting frame joint comprises a first half and a second half; and the pivotal connecting means further comprises restraining means for holding each frame joint half fixed relative to one of the carriages, both frame joint halves being restrained by the restraining means for straight-line motion, and one frame joint half being restrained by the restraining means and the other frame joint half being displaced by the hydraulic piston-cylinder means for turning.
 6. A tractor-shovel as in claim 5 wherein the hydraulic piston-cylinder means and the restraining means comprise a first hydraulic piston-cylinder aggregate and a second hydraulic piston-cylinder aggregate, each pivotally connected to one of the carriages and one of the frame joint halves.
 7. A tractor-shovel as in claim 5 wherein: the double-acting frame joint includes a frame joint plate connecting the first and second joints; and the hydraulic piston-cylinder means and the restraining means comprise a first hydraulic piston-cylinder aggregate and a second hydraulic piston-cylinder aggregate, each pivotally connected to one of the carriages and to the frame joint plate.
 8. A tractor-shovel as in claim 5 wherein the restraining means is actuated by a tooth-wheel drive. 